Not applicable.
Not applicable.
The present invention relates to rotatable drive arrangements. In particular, the present invention relates to a rotatable drive arrangement having a torque coupler which enables the driven portion of the arrangement to enter into and remain in each of an engaged state and a disengaged state while the driven portion is installed in relation to the drive portion.
A variety of different machines employ drive coupling systems in which the driven portion of the coupling system must be periodically separated and removed from the drive train or drive portion of the system for various reasons. For example, drive coupling systems can be employed in conventional plate planters with seed meters. During planting, the seed meter often fills with dirt, chaff and other foreign matter, and consequently it is typically necessary to periodically remove the seed meter for cleaning. Also, it sometimes is necessary to remove the seed meter in order to change a seed plate of the seed meter.
U.S. Pat. No. 6,003,454 to Ozers et al. (hereinafter referred to as xe2x80x9cthe ""454 patentxe2x80x9d), which issued on Dec. 21, 1999, is assigned to the assignee of the present patent application, and is hereby incorporated by reference herein, discloses a drive coupling system that can be employed in a conventionally known plate planter with a seed meter. The drive coupling system disclosed in that patent allows the driven portion to be removed/uninstalled or inserted/installed simply by vertically lifting or lowering the driven shaft relative to the drive shaft along a direction that is other than along the axes of the shafts.
More specifically, the system of the ""454 patent includes first and second torque couplers on a drive shaft and driven shaft, respectively, each of which includes a pair of lugs or protrusions. When the driven portion (including the second torque coupler and driven shaft) is installed relative to the drive portion, the lugs of each torque coupler are positioned diametrically opposite one another on the respective torque coupler. When installed, the distance between the lugs of each pair is the same, such that the lugs of each pair are aligned with and interface respective lugs of the other pair, thus allowing torque provided via the drive shaft and first torque coupler to be transferred to the second torque coupler and the driven shaft.
While the pair of lugs of the first torque coupler are attached to the remainder of the first torque coupler at specific positions, the pair of lugs of the second torque coupler are respectively mounted on first and second gears that are rotatably mounted on the remainder of the second torque coupler. The gears are engaged with one another so that the gears can only rotate relative to one another in opposite directions. Springs are employed tending to rotate the gears so that the lugs of the second torque coupler tend to move toward their default, diametrically-opposed positions. However, because the lugs of the second torque coupler are mounted on the rotatable gears, the lugs need not and do not remain in their diametrically opposed positions when force is applied to remove or install the driven shaft with respect to the drive shaft. Rather, the lugs move relative to one another so that one or both of the lugs can slip past the lugs of the first torque coupler as the second coupler is installed or removed.
Although in some applications it is desirable for the driven portion to be engaged to the drive portion whenever the driven portion is installed, this is not necessarily the case. Rather, in some applications it is desirable for the driven shaft to be disengaged from the drive shaft such that rotation of the drive shaft does not produce rotation of the driven shaft, even though the driven shaft remains installed in relation to the drive shaft. For example, in the case of a planter pulling a seed meter, while it may be desirable for the seed meter to operate to distribute seeds as the planter traverses most rows of a field, it may nevertheless be desirable for the seed meter to not distribute seeds with respect to certain rows of the field. Given the inconvenience of remove the seed meter each time the planter enters one of these rows, it would be desirable if the driven shaft could be temporarily disengaged from the drive shaft without entirely uninstalling the seed meter.
To address this need, the ""454 patent (particularly with reference to FIGS. 10-15 of that patent) discloses different xe2x80x9clock-out mechanismsxe2x80x9d that allow for a driven portion to be disengaged from a drive portion even thought the driven portion remains installed with respect to the drive portion. In one embodiment shown in FIGS. 10-11 of the ""454 patent, a key lock 570 slidably mounted on a support portion and is capable of sliding in and out of a detent 568 on one of the gears when the gears are rotated so that the lugs are rotated inwards toward one another. When the key lock 570 is slid into the detent 568, the gears are prevented from rotating so that lugs are rotated outwards, despite the springs on the gears. Consequently, the lockout mechanism when engaged maintains the lugs of the second torque coupler in an inward position such that the driven portion is disengaged from the first torque coupler.
An alternate embodiment of lock-out mechanism shown in FIGS. 12-15 of the ""454 patent employs a shaft that can be upwardly or downwardly actuated with respect to the support when the gears are rotated inward so that the lugs on the gears are rotated inward. If the shaft is upwardly actuated, then the shaft blocks outward rotation of the gears and thus maintains the lugs in their inward position such that the driven portion is disengaged from the first torque coupler. Additionally, the ""454 patent indicates that one or both of the gears could have an additional hook member or other means that was adapted to releasibly engage the other of the gears to maintain the lugs of the gears in their inward position such that the driven portion is disengaged from the torque coupler.
The lock-out mechanisms shown in the ""454 patent are advantageous in that they make it possible for the driven portion to be disengaged and engaged from the drive portion regardless of whether the driven portion is installed. However, each of the lock-out mechanisms of the ""454 patent requires one or more specialized components that are mounted on the second torque coupler and/or one or both of the gears in order to provide the functionality (e.g., the key lock, shaft, hook member or other means). Further, in each embodiment, at least one of these additional components must be slidably or otherwise movably mounted on the second torque coupler and/or one or both of the gears so that the lock-out mechanism can be engaged or disengaged. Engagement or disengagement of the driven portion with respect to the drive portion necessarily involves a separate step in which one or more of these specialized components are moved in relation to one or both of the gears.
Because these lock-out mechanisms require these specialized components and additional step(s) of operation to engage or disengage the driven portion, use of the lock-out mechanisms adds to the cost and complexity of manufacturing the drive coupling systems, adds to the complexity of operating the drive coupling systems, and further can add to maintenance costs. For these reasons, it would be advantageous to have an improved drive coupling system that had a lock-out mechanism that did not require the specialized components shown in the ""454 patent.
The present inventor has recognized that it would be possible to modify the design of the gears employed on the driven torque coupler from the designs disclosed in the ""454 patent in such a manner that the gear teeth themselves would be capable of operating as a lock-out mechanism. In particular, the present inventor has recognized that, if a sufficient number of gear teeth are missing from the gears of the torque coupler, then the gears would be capable of slipping or falling out of alignment with respect to one another as the lug extensions (and lugs) of the torque coupler were rotated toward one another. Additionally, the present inventor has recognized that, if the gears further include appropriate protrusions that preclude the gears from slipping too far despite missing teeth, then it would be possible for the gears to become misaligned just so much as to become locked in place with respect to one another, particularly if the shape of the gear teeth is configured to facilitate such locking action.
In particular, the present invention relates to a drive coupling system that includes a rotatable drive shaft, a driven shaft, a first torque coupler coupled to one of the drive shaft and the driven shaft, and a second torque coupler coupled to the other of the drive shaft and the driven shaft. The first torque coupler includes first and second lugs, while the second torque coupler includes a support, a first member rotatably coupled to the support and including a first extension and a first plurality of gear teeth that extend only partly around the first member, and a second member rotatably coupled to the support and including a second extension and a second plurality of gear teeth that extend only partly around the second member. The first and second members are capable of being respectively rotated to first and second rotational positions beyond which the first plurality of gear teeth are able to at least begin to slip out of alignment with the second plurality of gear teeth. The relative slipping of the first plurality of gear teeth with respect to the second plurality of gear teeth is limited due to contact occurring between the first and second extensions as the slipping occurs. As the relative slipping occurs, a first gear tooth of one of the first and second pluralities of gear teeth interfaces a second gear tooth of the other plurality of gear teeth so that the first member becomes locked in position in relation to the second member.
The present invention additionally relates to a lock-out mechanism for implementation in a drive coupling system. The lock-out mechanism includes a support; first and second members having first and second pluralities of gear teeth, respectively, first and second extensions, respectively, and first and second lugs, respectively; and means for biasing the first and second members toward rotational positions so that the first and second lugs are in first and second positions, respectively. Each of the first and second members is rotatably coupled to the support and, due to engagement of at least some of the gear teeth of the first and second pluralities of gear teeth, the first and second members are at least partly restricted to rotational motions that are in opposition to one another. Further, the first and second members are capable of being rotated and locked in position so that the first and second lugs are locked in third and fourth positions, respectively. Additionally, the first and second members are locked in position when the first and second pluralities of gear teeth of the first and second members slip out of gear alignment so that a first gear tooth of one of the first and second pluralities of gear teeth is locked in relation to a second gear tooth of the other of the first and second pluralities of gear teeth.
The present invention further relates to a method of disengaging a coupling of first and second torque couplers of a drive coupling system in a work vehicle, where the drive coupling system includes a drive shaft, a driven shaft, and the first and second torque couplers respectively coupled to respective ones of the drive and driven shafts, where first and second lugs are fixedly positioned on a first support of the first torque coupler, the first and second members are rotatably coupled to a second support of the second torque coupler, and third and fourth lugs are fixedly positioned on the first and second members, respectively, and where the first and second members respectively include first and second pluralities of gear teeth to allow for engagement between the first and second members, the first and second members being at least partly restricted by the pluralities of gear teeth to rotational movements in opposite directions in relation to one another. The method includes applying a torque to at least one of the first and second members so that the first and second members respectively rotate to positions beyond which slipping can occur between the first and second pluralities of gear teeth of the first and second members. The method additionally includes applying a further torque to one of the first and second members so that a first gear tooth of the one member becomes wedged against a second gear tooth of the other of the first and second members, wherein the wedging of the first gear tooth against the second gear tooth locks both teeth and both members substantially in their respective positions.
These and other aspects of the invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention and reference is made therefore, to the claims herein for interpreting the scope of the invention.